JPH09178306A - Refrigeration cycle equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly judge insufficiency of the refrigerant irrespective of connection/disconnection of the operation of a compressor in a refrigeration cycle device to judge insufficiency of the refrigerant based on the temperature of an evaporator. SOLUTION: Insufficiency of the amount of the refrigerant sealed in the cycle is judged based on the temperature drop of an evaporator 9 when a prescribed time is elapsed after a compressor 1 is started. On the other hand, once the compressor 1 is stopped, the judgment of insufficiency of the amount of the refrigerant by the temperature drop of the evaporator 9 is prohibited. Mistaken judgment of the insufficient refrigerant can surely be prevented when the temperature of the evaporator 9 does not sufficiently rise when the compressor 1 is re-started. As a result, insufficiency of the amount of the refrigerant sealed in the cycle can constantly and surely judged based on the temperature drop of the evaporator 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a shortage of refrigerant in a refrigeration cycle device, and is suitable for use in, for example, a refrigeration cycle device for an automobile air conditioner.

[0002]

2. Description of the Related Art Conventionally, in Japanese Unexamined Patent Publication (Kokai) No. 1-95255, as a method for detecting a shortage of the amount of refrigerant in a refrigeration cycle device, the temperature of an evaporator at the time of starting a compressor,
It is proposed to calculate the temperature difference from the temperature of the evaporator after a lapse of a predetermined time after starting the compressor, and to judge that the amount of refrigerant enclosed in the cycle is insufficient when this temperature difference is below a predetermined value. ing.

[0003]

However, if the shortage of the refrigerant amount is determined based on only the degree of decrease in the evaporator temperature after the compressor is started as described above, the following problems occur. For example, in a car air conditioner,
It is often practiced to detect the temperature of the evaporator and interrupt the operation of the compressor according to the temperature of the evaporator to prevent the frost of the evaporator. In such a refrigeration cycle apparatus, in a state in which the operation of the compressor is intermittently controlled, the temperature of the evaporator has already dropped sufficiently when the compressor is restarted, so the degree of decrease in the evaporator temperature after the startup of the compressor Is small, so despite the fact that the amount of refrigerant is normal,
There may be a case where it is erroneously determined that the refrigerant is insufficient.

Also, when the operation of the vehicle air conditioner is completely stopped and the operation of the vehicle air conditioner is resumed after a short time, the same problem occurs because the evaporator temperature has not risen sufficiently. The present invention has been made in view of the above points, in a refrigeration cycle apparatus that determines a refrigerant shortage based on the evaporator temperature, regardless of whether the compressor operation is intermittent, it is possible to accurately determine the refrigerant shortage. To aim.

[0005]

In order to achieve the above object, the present invention employs the following technical means. That is, in the invention according to claim 1, the shortage of the amount of refrigerant enclosed in the cycle is determined based on the amount of temperature decrease of the evaporator (9) after a predetermined time has elapsed after the compressor (1) is started,
When the compressor (1) is once stopped, it is characterized in that, after the stop, a determination of the refrigerant amount shortage due to the temperature decrease amount of the evaporator (9) is prohibited for a predetermined period.

In this way, after the compressor (1) is stopped, the determination of the insufficient amount of the refrigerant is prohibited for a predetermined period of time, so that the temperature of the evaporator (9) rises sufficiently when the compressor (1) is restarted. If not, it can be reliably prevented that the refrigerant is deficiently deficient, and as a result, the deficiency of the amount of refrigerant enclosed in the cycle can always be accurately determined based on the temperature decrease amount of the evaporator (9). Can be determined.

According to the second aspect of the present invention, the previous temperature decrease amount of the evaporator (9) is stored, and during the predetermined period, it is based on the previous temperature decrease amount of the evaporator (9). It is characterized by determining whether or not the amount of refrigerant enclosed in the cycle is insufficient. Therefore, even if the determination that the amount of refrigerant is insufficient due to the actual temperature decrease amount of the evaporator (9) is prohibited for a predetermined period after the compressor (1) is stopped, the previous temperature decrease amount of the evaporator (9) is set. Based on this, it is possible to determine whether the refrigerant is insufficient.

Further, in particular, in the invention described in claim 7, the refrigeration cycle for controlling the cooling capacity of the evaporator (9) by interrupting the operation of the compressor (1) according to the temperature of the evaporator (9). The device is characterized in that when the operation of the compressor (1) is stopped, a timer for measuring the elapsed time after the stop of the compressor (1) is reset. This allows
Even if the operation of the compressor (1) is frequently interrupted for controlling the cooling capacity of the evaporator (9), the lack of the refrigerant amount can always be accurately determined without being affected by the operation.

The reference numerals in parentheses indicate the correspondence with the concrete means described in the embodiments described later.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a refrigeration cycle device for an automobile air conditioner to which the present invention is applied. The compressor 1 has an electromagnetic clutch 2, and when the electromagnetic clutch 2 is in a connected state, the belt 3 is released. The compressor 1 is driven by the vehicle traveling engine 4 via the engine.

The compressor 1 sucks in and compresses a gas refrigerant, and discharges a high temperature and high pressure superheated gas refrigerant. The gas refrigerant discharged from the compressor 1 flows into the condenser 5, where it is cooled and condensed by the cooling electric fan 6. Then, the refrigerant flowing out from the condenser 5 flows into the receiver 7, where the gas-liquid of the refrigerant is separated. This receiver 7
The liquid refrigerant separated in (1) is decompressed by the temperature type expansion valve (pressure reducing means) 8 to be a low temperature low pressure gas-liquid two-phase state, and flows into the evaporator 9. The evaporator 9 is housed in an air conditioning case 10 of an automobile air conditioner and exchanges heat (heat absorption) with inside air or outside air blown by an air conditioning electric fan 11 to evaporate a refrigerant. The air blown from the air-conditioning fan 11 is cooled and dehumidified by the evaporator 9 to become cold air, and is reheated to a predetermined temperature by a heater core 12 that heats air by using engine cooling water as a heat source, and then a predetermined air outlet (see (Not shown) is blown out into the passenger compartment. Reference numeral 13 is a temperature control door (air mix door) for controlling the blown air temperature by adjusting the amount of heating by the heater core 12.

The gas refrigerant evaporated in the evaporator 9 is sucked into the compressor 1 through the refrigerant suction passage 14. The temperature type expansion valve 8 adjusts the valve opening degree (refrigerant flow rate) according to the temperature and pressure of the evaporator outlet refrigerant so that the degree of superheat of the refrigerant at the outlet of the evaporator 9 becomes a predetermined value. There is. An air-conditioning electronic control unit 20 is composed of a micro-computer and its peripheral circuits, and controls the operation of the air-conditioning equipment according to a preset program. Reference numeral 21 denotes a temperature sensor including a thermistor or the like for detecting the temperature of the evaporator 9. In this example, the temperature sensor 21 is arranged at a portion of the evaporator 9 immediately after the air blow, and detects the air temperature immediately after the air blow. This temperature sensor 2
The detection signal 1 is used not only for detecting the shortage of the refrigerant but also for controlling the cooling capacity (frost prevention) of the evaporator 9 as described later.

Therefore, the temperature sensor 21 experimentally obtains the lowest temperature portion immediately after the evaporator 9 blows,
It is installed at the location with the lowest temperature. Since the temperature sensor 21 only needs to be able to detect the temperature of the evaporator 9, it may be closely attached to the fins of the evaporator 9 to detect the fin surface temperature and the like. Reference numeral 22 denotes an outside air temperature sensor that detects the outside air temperature.
It is installed in a position where the outside air around it can easily flow in. 23
Is a sensor group for automatic air conditioning control, which is a solar radiation sensor that detects the amount of solar radiation, an inside air sensor that detects the temperature inside the vehicle, and a heater core 1.
2 includes a cooling water temperature sensor and the like.

Further, an air conditioning control panel (not shown) installed on the instrument panel at the front of the passenger compartment is provided with a group of operation switches 24 for instructing an air conditioning operation. Of the operating switch group 24, the air-conditioning switch 25 includes a switch 25a for outputting a start signal of the compressor 1, and It has a lamp 25b for displaying the closed state of the switch 25a.

Here, the lamp 25b blinks when the amount of the refrigerant is insufficient to indicate that the refrigerant is insufficient, and also serves as a refrigerant insufficient display means. Of course, lamp 25
In addition to b, a dedicated display means may be provided for indicating the lack of the refrigerant. Next, the operation of the above configuration will be described.
First, the operation as a refrigeration cycle will be described. When the electromagnetic clutch 2 is energized by the control device 20 and the electromagnetic clutch 2 is in the connected state, the compressor 1 is connected to the automobile engine 4 and the compressor 1 operates. Then, the refrigerant is sucked and compressed. Then, the gas refrigerant discharged from the compressor 1 is cooled and condensed in the condenser 5.

The gas-liquid of the refrigerant flowing out from the condenser 5 is separated by the receiver 7, and the liquid refrigerant (saturated liquid refrigerant) separated by the receiver 7 is decompressed by the temperature type expansion valve 8 to be a low-temperature low-pressure gas. The liquid becomes a two-phase state, this refrigerant is evaporated in the evaporator 9, and the gas refrigerant evaporated in this evaporator 9 is sucked into the suction passage 14.
And is again sucked into the compressor 1. Also, the evaporator 9
Immediately after the temperature is blown, the temperature sensor 21 detects the temperature, and when the detected temperature falls below a set temperature (for example, 3 ° C.), the controller 20 cuts off the energization of the electromagnetic clutch 2 and the compressor 1 stops. . Then, by stopping the compressor 1, the temperature immediately after the blowout of the evaporator 9 is set to a set temperature (for example,
When the temperature rises to 4 ° C), the control device 20 energizes the electromagnetic clutch 2 and restarts the compressor 1.

In this way, the operation of the compressor 1 is interrupted according to the temperature immediately after the blowing of the evaporator 9, so that the evaporator 9
To prevent frost. By the way, in such a refrigeration cycle device, the amount of refrigerant enclosed in the cycle,
The relationship with the temperature decrease amount of the evaporator 9 after the compressor 1 is started is as shown in FIG. The amount of temperature decrease of the evaporator 9 in FIG. 2 is the evaporator temperature T ₁ when the compressor 1 is started and the evaporator temperature T ₁ when a predetermined time (1 minute in this example) has elapsed since the compressor 1 was started. Temperature difference from ₂ (T ₁ −T ₂ = Δ
T).

As shown in FIG. 2, this temperature difference (T ₁ -T
₂ ) gradually increases until the amount of refrigerant enclosed in the cycle decreases to around 50%. Thus, the temperature difference (T ₁ −
The reason why T ₂ ) becomes large is that the evaporation pressure decreases as the amount of refrigerant decreases, and the evaporation temperature near the inlet of the evaporator decreases accordingly. However, when the amount of refrigerant further decreases below around 50%, in the evaporator 9, the overheated gas region of the refrigerant sharply increases and the cooling capacity sharply decreases, so that the temperature difference (T ₁ −T ₂ ).
Also sharply decreases.

Therefore, in FIG. 2, the amount of refrigerant is 100%.
Temperature difference (T₁-T _Two) Smaller than
Set value T for determining the refrigerant shortage in the range₀(For example, 5.5
If you set ° C), this set value T₀More temperature difference
(T₁-T_Two) Is small, the amount of refrigerant enclosed in the cycle is
It can be determined that there is a shortage. However, the operation of the compressor 1
Intermittent to prevent frost mentioned above, or
Frequent interruptions due to intermittent operation of the air conditioner
In this state of frequent intermittent compressor operation,
Since the evaporator temperature remains low when the compressor 1 is restarted,
Even if the amount of refrigerant is normal, the temperature difference (T₁-T_Two)But
Set value T₀The smaller case occurs.

Therefore, if the intermittent operation of the compressor is not considered,
In reality, it is not possible to accurately detect the insufficient amount of refrigerant without erroneous detection. Therefore, the present invention intends to propose an accurate refrigerant amount shortage detection device in consideration of the intermittent operation of the compressor. Next, the operation of the refrigerant amount shortage detection according to the present invention will be described with reference to the flowchart of FIG. To explain.

When the air-conditioning electronic control unit 20 is electrically connected to the vehicle-mounted power supply battery, the control flow of FIG. 3 is started upon receiving power supply, and in step S1, whether or not the compressor 1 is started (specifically, Is ON / OFF of the electromagnetic clutch 2)
When the compressor 1 is started, it is determined in step S2 whether the elapsed time t _off after the previous stop of the compressor 1 has passed a predetermined time (for example, 120 minutes).

When the elapsed time t _off exceeds 120 minutes, the process proceeds to step S3, and the evaporator temperature T ₁ at the time of starting the compressor ₁ is stored. Next, in step S4, it is determined again whether or not the compressor 1 is started up. When the compressor 1 is running, the process proceeds to step S5, and the elapsed time t _on after the start-up of the compressor 1 is a predetermined time (for example, 1 minute) Determine if it has elapsed.

If the elapsed time t _on exceeds 1 minute, the evaporator temperature T ₂ after the elapse of a predetermined time from the startup of the compressor 1 is stored in step S6. Next, in step S7, the temperature difference ΔT = between the evaporator temperatures T ₁ and T ₂
It is determined whether T ₁ -T ₂ is smaller than the set value T ₀ (5.5 ° C). When the temperature difference ΔT is smaller than the set value T ₀ (5.5 ° C.), it is determined from the characteristics of FIG.
In step S8, the lamp 25b of the air-conditioning switch 25 is made to blink, and the occupant in the vehicle compartment is informed of the shortage of the refrigerant.

In step S7, the temperature difference ΔT = T ₁
When −T ₂ is larger than the set value T ₀ (5.5 ° C.), the amount of refrigerant is normal, so that step S8 is bypassed and the process directly proceeds to step S9 to determine whether the compressor 1 is stopped. If the compressor 1 is stopped, step S10 is performed.
Then, the timer for measuring the elapsed time t _off after the compressor 1 is stopped is reset (t _off = 0), and the process returns to step S1.

On the other hand, the elapsed time t after the previous stop of the compressor 1
_offWhen the specified time (for example, 120 minutes) has not elapsed
Does not raise the temperature of the evaporator 9 to near room temperature,
Is held. So in such cases, step
The determination in S2 is NO, the process proceeds to step S11, and here
Then, the temperature difference ΔT when the compressor was started last time is the set value T ₀
(5.5 ° C) It is determined whether it is smaller than. Previous temperature difference Δ
T is the set value T₀When it is higher than (5.5 ° C), it is a refrigerant
Since the amount is normal, the process proceeds to step S9. That is,
According to the temperature decrease amount of the evaporator 9 in steps S3 to S8.
"Insufficient amount of refrigerant is not displayed," is not displayed.

This makes it possible to prevent the erroneous detection of the shortage of the refrigerant when the compressor 1 is restarted shortly after the previous stop of the compressor 1. Further, the operation of the compressor 1 is frequently interrupted according to the temperature of the evaporator 9 in order to prevent the frost of the evaporator 9, and even with respect to this frequent disconnection, compression is performed by the determination in steps S4 and S9. Immediately after the stop of the machine 1, the process proceeds to steps S10 and S12, and the elapsed time t _off after the compressor 1 is stopped is reset to 0, so that the erroneous detection of the lack of the refrigerant can be similarly prevented.

Also, the temperature difference at the time of the previous compressor startup
ΔT is the set value T₀When it is lower than (5.5 ° C), it is cold.
Since the medium is insufficient, in step S13, the air conditioning switch
By blinking the lamp 25b of No. 25, the shortage of refrigerant is detected in the passenger compartment.
Display to crew. Therefore, according to steps S3 to S8
“Determination of insufficient amount of refrigerant due to the amount of temperature decrease in the evaporator 9, refrigerant
"Insufficient display" is not performed (in other words, if the amount of refrigerant is insufficient,
Even if you prohibit the judgment), no problem occurs. (Second Embodiment) In the first embodiment, in step S2
Elapsed time t since the last stop of compressor 1_offThe size of
However, in step S2, the temperature sensor 21
Detected by the outside temperature sensor 22
The temperature difference from the outside air temperature is below a specified value (eg 1 ° C)
It is determined whether the temperature is within
During a certain period of time, "the insufficient amount of refrigerant due to the temperature decrease amount of the evaporator 9 is determined.
You may make it prohibit. (Third Embodiment) When the refrigerant shortage progresses,
Lubrication oil return deteriorates, leading to poor lubrication of the compressor 1.
Stop the compressor 1 when the refrigerant is insufficient
You may make it. For example, in the characteristic diagram of Fig.
Then, the temperature decrease amount ΔT (T ₁-T_Two) Is the set value
T₀If it is smaller, the lamp 25b blinks to cool.
The shortage of the medium is displayed, and the temperature decrease amount ΔT (T (T₁-T
_Two) Is the set value T₀Second smaller set value T₀′
If it is too small, the lamp 25b blinks and the refrigerant is insufficient.
The compressor 1 may be stopped at the same time as is displayed.
Yes. (Fourth Embodiment) In the refrigeration cycle of the first embodiment,
Depending on the evaporator temperature detected by the temperature sensor 21
By intermittently controlling the operation of the compressor 1, the flow of the evaporator 9 is controlled.
I try to prevent the loss, but as shown in Figure 4.
, An evaporation pressure adjusting valve 15 is installed on the refrigerant downstream side of the evaporator 9.
The evaporation pressure of the evaporator 9 is adjusted by the evaporation pressure adjusting valve 15.
By adjusting the opening of the refrigerant passage according to
Keep the evaporation pressure of 9 above the set value and
Even in the refrigeration cycle that prevents the frost of the generator 9,
The present invention can be applied.

Similarly, as the compressor 1, a variable capacity compressor whose discharge capacity can be changed is used, and the capacity of this variable capacity compressor is varied according to the suction pressure (evaporation pressure of the evaporator 9) to form an evaporator. The present invention can also be applied to the refrigeration cycle in which No. 9 frost is prevented. (Other Embodiments) In the flowchart of FIG. 3, the refrigerant shortage determination in steps S3 to S7 is repeatedly executed. However, if the refrigerant shortage is determined once in step S7, then unconditional It is also possible to maintain the determination result of the refrigerant shortage so that the refrigerant shortage determination is not repeated.

In the refrigeration cycle of the first embodiment, the case where the compressor 1 is driven by the vehicle engine 4 has been described, but the present invention can be applied to a refrigeration cycle in which the compressor 1 is driven by an electric motor. Is.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram showing a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a temperature decrease amount of the evaporator and a refrigerant charge amount after the compressor is activated.

FIG. 3 is a flowchart showing the operation of the first embodiment of the present invention.

FIG. 4 is a refrigeration cycle diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Electromagnetic clutch, 5 ... Condenser, 8 ... Expansion valve, 9 ... Evaporator, 14 ... Refrigerant intake passage, 20 ... Control device, 21 ... Temperature sensor, 22 ... Ambient temperature sensor, 25b ...
lamp.

Claims (8)

[Claims] 1. A compressor (1) for compressing and discharging a gas refrigerant.
A condenser (5) for condensing the gas refrigerant discharged from the compressor (1), a decompression means (8) for decompressing and expanding the liquid refrigerant condensed by the condenser (5), and a decompression means ( 8) an evaporator (9) for evaporating the refrigerant decompressed and expanded in 8), a refrigerant suction passage (14) for sucking the gas refrigerant evaporated in the evaporator (9) into the compressor (1), and the evaporator (9) 9) Temperature detecting means (2) for detecting the temperature
1) and the detection signal of this temperature detection means (21) are input, and based on the temperature decrease amount of the evaporator (9) after a predetermined time has elapsed after the start of the compressor (1), the refrigerant enclosed in the cycle is filled. A refrigeration cycle apparatus, characterized in that it is determined that the amount of refrigerant is insufficient and that the determination of the amount of refrigerant that is insufficient due to the temperature decrease amount of the evaporator (9) is prohibited for a predetermined period after the compressor (1) is stopped. 2. The amount of refrigerant enclosed in the cycle is stored based on the previous amount of temperature decrease of the evaporator (9), and is stored based on the amount of previous temperature decrease of the evaporator (9) during the predetermined period. The refrigeration cycle apparatus according to claim 1, wherein a shortage of the temperature is determined. 3. The predetermined time period is determined by the elapsed time after the compressor (1) is stopped.
Or the refrigeration cycle apparatus according to 2. 4. The method according to claim 1, wherein the predetermined period is determined by a temperature difference between the temperature of the evaporator (9) and the outside air temperature after the compressor (1) is stopped. The refrigeration cycle apparatus according to any one of claims. 5. The refrigerant amount shortage display means (25b) is operated when it is determined that the amount of refrigerant enclosed in the cycle is insufficient.
Refrigeration cycle device described in. 6. The refrigeration cycle according to claim 1, wherein the compressor (1) is stopped when it is determined that the amount of refrigerant enclosed in the cycle is insufficient. apparatus. 7. The cooling capacity of the evaporator (9) is controlled by intermittently operating the compressor (1) according to the temperature of the evaporator (9). The refrigeration cycle apparatus according to claim 4, wherein when the operation of (1) is stopped, a timer for measuring an elapsed time after the stop of the compressor (1) is reset. 8. A refrigeration cycle apparatus according to any one of claims 1 to 7, wherein the compressor (1) is driven by an automobile engine, and cool air cooled by the evaporator (9) is provided. An air conditioner for a vehicle, characterized in that air is blown into the vehicle interior to cool the vehicle interior.